Because hydrogen has excellent cooling characteristics, it is often utilized to cool the internals of electric generators. FIG. 1 illustrates a conventional hydrogen-cooled generator 10. The generator 10 includes a rotor 11 and a stator 12 enclosed by a housing or shell 13. The rotor 11 generally includes a set of blades 14 for propelling hydrogen around the interior of the generator to promote cooling. The directed line segments in FIG. 1 illustrate typical flow patterns for hydrogen in a hydrogen-cooled generator.
Generators that utilize hydrogen for cooling often include a generator-condition monitor for detecting overheating within the generator. The condition monitor takes samples of hydrogen gas from the generator and monitors the samples for signs of overheating. When materials within the generator are heated sufficiently to cause thermal decomposition, the materials produce concentrations of sub-micron particles, referred to as pyrolytic products or pyrolytic particulates. The condition monitor can identify an overheat condition by detecting the presence of pyrolytic products in a hydrogen sample.
A significant problem with conventional generator-condition monitors is that the condition monitor remote from the generator and hydrogen samples must be conveyed to the monitor by a complex system of pipes and valves. This transfer of hydrogen away from the generator raises safety concerns by significantly extending the hydrogen zone. Although pure hydrogen is a non-explosive medium, it can become extremely dangerous when it is mixed with air. Therefore, the pipes and valves used to convey hydrogen samples to and from a remote condition monitor must be specially designed to carefully guard against hydrogen leaks, which adds significant cost and complexity to an electric generator.